U.S. Pat. No. 4,223,031 describes the antiallergic agents 3-(1H-tetrazol-5-yl)-4H-pyrimido[2,1-b]-benzothiazol-4-ones and 6-(1H-tetrazol-5-yl)thiazolo[3,2-a]-pyrimidin-5-ones and methods for their synthesis. Unfortunately, the synthetic methods described therein generally require several steps and are therefore not particularly convenient.
Sam and Plampin, J. Pharm. Sci., 53,538 (1964) describes the synthesis of substituted 2-aminobenzoxazoles and substituted benzoxazolinones.
Ethyl tetrazol-5-ylacetate is described by Finnegan, et al., J. Am. Chem. Soc., 80,3908 (1958). It is used to prepare 5-phenyltetrazole and various other substituted tetrazoles.